W30 - Experiments console (A/B)

One A/B framework for three things that are usually tested in three different tools: AI model canaries (fed from the W29 lifecycle), ad creative, and unlisted segment-specific landing pages. Guardrails are platform-level: minimum sample before reading results, auto-stop on guardrail-metric regression, and consent-aware assignment - unlisted pages are targeted, never deceptive, and disclose tracking like any other page.